1. Field of the Invention
The present general inventive concept generally relates to a power supply apparatus and an image forming apparatus having the same, and more particularly, to a power supply apparatus capable of outputting a constant voltage or a constant current according to an environment surrounding an image former of an image forming apparatus, and an image forming apparatus having the same.
2. Description of the Related Art
An image forming apparatus is a device that performs generation, print, reception, and transmission of image data. Image forming apparatuses include printers, scanners, photocopiers, facsimile machines (fax), and multifunction peripherals that incorporate the functionality of multiple devices in one.
In the related art, an image forming apparatus supplies a high voltage to an image former using a high voltage power supply (HVPS) to form an image. The supplied high voltage is applied to the image former in a constant voltage control method or a constant current control method. At this time, there is an advantageous control method according to a surrounding environment such as a temperature or humidity.
When printing in an environment with a high temperature and high humidity, the constant voltage control method is preferably used to supply the high voltage to the image former to avoid an electrical current leakage around paper, which often occurs when the constant current control method is used in the same environment deteriorating image quality of a printout.
When printing in an environment with a low temperature and low humidity, since a voltage may be applied fluidly according to the load of paper or a roller, it is more advantageous to apply a high voltage to the image former in the constant current control method rather than the constant voltage control method.
However, since a power supplier of a conventional image forming apparatus supplies the high voltage to the image former by adopting only either the constant current control method or the constant voltage control method, but not both, it is impossible to form an image in a control method that can switch between the constant control method and the constant voltage method by taking into consideration of the surrounding environment.
Therefore, there is a need for an image forming apparatus having a power supply apparatus which has both constant voltage and constant current feedback circuits to provide an image former with the high voltage by sensing the surrounding environment to selectively apply a more advantageous control method.